Scientists find rare butterfly on Biscayne Bay island

Researchers hunting for one of the world’s rarest butterflies on Monday announced that they captured a single female in the mosquito-filled forest of Elliott Key.

That may not sound like much but the discovery last week gives scientists a shot at producing lab-bred Schaus swallowtails to boost a population that experts fear is fast fluttering toward extinction.

“It at least gives us some hope,’’ said Jaret Daniels, a University of Florida butterfly expert leading a recovery effort that includes state and federal wildlife agencies and Biscayne National Park.

Last year, researchers found only four males on the island in Biscayne Bay, prime habitat for the endangered butterfly. This year, in addition to the female, they also found seven larvae, suggesting other females also may be breeding, Daniels said.

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The netted female was kept in an enclosure in the wild for four days before being released but laid only one egg, a “disappointing” production Daniels blamed on the heavy rains of the last few weeks. Females can produce hundreds of eggs during their brief “flight” or breeding season.

Still, with the additional larvae, he said, it could be enough to move forward with a captive breeding if needed. The breeding program, run in a Gainesville lab, helped boost the population in the mid-1980s and 1990s.

Like a dozen or so other South Florida butterflies — most notably the Miami Blue, which is now confined to a few colonies in isolated islands off Key West — the Schaus has been in decline for decades. It was first listed as “threatened” in 1976 then elevated to the most serious “endangered’’ category in 1984 as the population plummeted, largely as a result of pesticide spraying for mosquito control and development destroying the coastal forests they call home.

In an effort to expand breeding habitat, Biscayne National Park last year planted a large stand of young torchwood trees and also other few key “host plants” that females will deposit their eggs on.

Larry Williams, Florida state supervisor for ecological services for the U.S. Fish and Wildlife Service, which manages endangered species and is supporting the annual Schaus hunts, said teams would continue to search for more females throughout the remaining breeding season, which typically ends around mid-June.

While the find does not assure the species will survive, Williams said, “The despair we felt last year has been replaced by hope.”